1. Field of the Invention
The present invention relates to machine components in general and in particular to a universal spring biased device having a plunger, which may receive a first and second attachment.
2. Discussion of the Related Art
Spring loaded machine components and tools are well known in the art. For example, various spring loaded fixturing components can be used as clamping mechanisms for various tool and machine applications. These conventional spring-loaded devices are individually designed for many different applications. This forces manufacturers, distributors or users to keep a large assortment on hand. Often a custom device must be designed and built because a standard device is not available with the correct features. Applications include, but are not limited to, holding, locating, stopping, braking, cushioning, indexing, latching, push or pull pins, and remote control applications.
Conventional spring loaded devices also generally have a hollow center for receiving a plunger. Typically, such conventional spring loaded devices have a single fixed attachment for a specialty function such as being received in a detent. However, what is needed is a spring-loaded device, which is useful for a wide universe of applications. What is also needed is a device that is easily adapted for many applications using standard or custom add-on components and attachments.
The spring-biased device of the present invention is comprised of a steel cylindrical body having an orifice. A hardened steel cylindrical plunger is received in the orifice and held in place by means of a jam nut or other device. The spring surrounds the plunger and is operably contained between the plunger and the body. The plunger has a first end or compression end and a second end or tension end. The first end has a hole therein for receiving a first attachment. The second end has threads for receiving a second attachment. A retracting lock maybe attached to the second end to engage the body and ensure that the plunger""s movement is limited. The body is constructed of round stock and may have at least one flattened side. Preferably, the body has two flattened sides so that the body can be held steady with a conventional wrench during attachment and detachment or prevent interference with burrs caused by set screw mounting. Further, the flats engages tangs of the retractable lock to prevent movement.
A clamp is preferably associated with the body for attachment of the device to a mounting or support member. In one preferred embodiment a split clamp having an upper clamp portion and a lower clamp portion is used to form a mounting block for attachment of the body to the mounting member. At least one screw secures the clamp portions to each other and thereby restricts the movement of the body.
The plunger preferably has an axial groove. There may also be a groove in the body for receiving a key. A key may also fit into the axial groove to restrict the movement of the plunger. The plunger may also have preferably two flattened sides so that it can be held steady by a wrench during tightening. The hole at the plunger first end preferably has tapped threads to engage threads on the first attachment. The plunger second end preferably has an extension with threads along its length to engage the threads contained in the hole in the second attachment. The threaded hole of the second attachment and the threaded extension of the first attachment can receive a variety of attachments such as knobs, bolts, stopping members, gripping contact bolts, wheels, etc. Therefore, the tool may be used in both tension and compression applications.
The inventive tool may further be a precision spring-loaded cylinder of universal design for use in custom automation and fixturing applications. For example, unlike current spring stops and plungers, this tool may have tapped holes with a pilot hole on the end of the plunger for easy attachment of standard or custom details. A range of sizes is available to obtain the optimum spring force, and stroke and plunger diameter combinations for a multitude of applications. An optional retracting lock and a split-clamp-mounting block can also be provided. The device may be welded, bonded, or press fit into place on the mounting member.
Because the preferred body is made from round stock instead of the threaded body found on many conventional devices, the inaccuracies inherent with thread runout are avoided. The universal spring devices are made to close tolerances in order to handle accurate indexing applications as well as many other applications. Hardened steel plungers extend completely through the body, providing a large bearing surface for side and offset loading. Moreover, when used in typical spring stop applications, the body can be easily adjusted axially whereas conventional spring stops cannot.
In one preferred embodiment, the split clamp mounting block has at least one clearance hole for mounting the block to the mounting member. The preferred embodiment of the clamping block has holes for receiving screws, which may be tightened by a wrench. In another preferred embodiment, the clamp may have a hole for receiving at least one set screw to hold the clamp in place relative to the body.
At least one of the tension and/or compression end may be chamfered so that the end can be received in a receiving cavity. In another preferred embodiment, a pilot hole is used for centering the attachments and helping to locate the attachment into the hole in the end of the plunger.
The plunger lock can preferably be retracted and rotated 90xc2x0 to lock the plunger in a retracted position. The retracting lock preferably attaches to the threaded extension at the tension end. The axial groove along the outer surface of the plunger allows air to escape from inside the body""s orifice and thus allows for smooth, rapid plunger actuation.
Dowel pin holes allow the clamps to be mounted to pins contained in the mounting member. The inventive device may be a long stroke device or a short stroke device. Also, a light spring or a heavy spring may be used depending on the application. The spring may have a spring force between 0.5 and 71.25 foot pounds. Additionally, a snap ring, cable or jam nut may be included for tensioning the spring. The body is preferably machined from cold rolled steel. The steel body device preferably has black oxide finish and the plunger is preferably made of case hardened steel with a black oxide finish. However, any steel or aluminum may be used. In other preferred embodiments stainless steel or other forms of carbon steel may be used to improve wear resistance, corrosion resistance, and heat resistance. In some applications nylon, delrin or other forms of plastic maybe used so as not to mar soft materials such as aluminum or brass. In other applications, the device may be made of a phenolic or other fiber/resin material. Close tolerances may also be desirable.
One of the advantages of using the spring-loaded device of the present invention is that it allows for accurate and repeatable end forces. Further, it allows for side loading, its easier to install then conventional standard springs, the projection is repeatable time after time, the spring has a minimal compression set, the spring loaded component can be used in a variety of products, machine tools, fixtures, and assembly tools, and it can vary in size and weight as illustrated by the table below.
In yet another preferred embodiment, a sensor is attached to at least one of the compression end or the tension end. The sensor senses the plunger""s movement.
In another embodiment, a remote actuating cable is attached to the tension end. The actuating cable moves the plunger relative to the body.
In still another embodiment, the invention may be used in a fixturing device in conjunction with a moving member.
Other applications include bumpers, stopping, indexing, latching, pull or push pinning, locating, holding, braking and other applications including remote applications.
These and other aspects of the present invention will be better appreciated and understood when considered in conjunction with the following description in the accompanying drawings. It should be understood however, that the following description, while indicating preferred embodiments of the present invention, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all modifications.